As is known in the art, wireless communication systems, such as Enhanced Data rate for GSM Evolution (EDGE), Wideband Code Division Multiple Access (WCDMA), and High Data Rate (HDR) CDMA, have radio resources that can be assigned to users adaptively based upon their channel conditions in order to optimize the overall system performance. The overall system performance for wireless systems is typically measured by the spectrum efficiency, in kbps/MHz/site, subject to a given user performance requirement (e.g. 90% of average user throughput should be higher than 50 kbps).
In the EDGE system, a radio resource includes a transmission power and a transmission format (modulation/coding). Each transmission format corresponds to one transmission rate. The transmission format is changed dynamically according to the measured channel conditions for maximizing user throughput. Power control can also be used to enhance system performance.
In WCDMA, the radio resources are represented by a transmission power and a spreading code with different spreading factors (i.e. Orthogonal Variable Spreading Factor (OVSF)). Different transmission rates can be achieved by varying the transmission power and code allocation. HDR is similar to WCDMA as both transmission power and spreading code can be varied to maximize the system throughput. However, determining an optimal power and transmission rate allocation for all the system users is quite challenging. In addition, known systems require a central controller for acquiring knowledge of propagation conditions for all of the active users in the system. Such systems are unable to achieve the optimal allocation of scarce radio resources.
It would, therefore, be desirable to provide a wireless system that overcomes the aforesaid and other disadvantages.